Residential land is very expensive - our friends have just paid 250,000 for a plot to build a 180m2 house in the suburbs, no views to speak of. Land with sea views will be more expensive. Building costs average out at anything between 1000 and 1500 per square metre, so their total cost is going to be fairly high. Building materials and fitting out can be as expensive as you want to make it from an IKEA kitchen to a bespoke build. Swimming pools of course just add to the bill, an average pool design is going to be minimum 20,000 if you want a decent job. We've just built a house on a family owned plot, so we didn't (thankfully) have to pay for it, but the planning process, getting designs passed through, obtaining permissions to build, checking borders with land registry, negotaiting boundary disputes with neighbours, oiling the cooperation of the municipality through the local muktar (mayor), arranging supply of electricity, water, getting permission to place a cess-pit along a road boundary, negotiating future road access to now landlocked neighbours agricultural land, notifying hunters of the proposed boundaries etc. was a long drawn out and fairly torturous affair and would have been nigh on impossible without my Greek speaking wife. We got to see quite a few building sites as we chose contractors and the majority of them were shockingly bad - poor workmanship, rip off merchants using cheap materials but charging for premium whilst owners are unable to check the site personally etc. We decided in the end to hire in a build company from abroad and put them up in a rented house, paid for their food and transport whilst they completed the build and it worked out cheaper than hiring local developers (whose quotes were astronomical in comparison. If you have building experience, it might work out cheaper to organise it yourself. Most villages have contacts that can supply resonable materials at decent costs -e.g. concrete, irons, hardcore and plant, but there is little experience here for newer materials (concrete is king)(another reason we looked abroad for an eco-friendly build).
Good luck with your search for a good plot...